linux/drivers/clocksource/arm_arch_timer.c
Marc Zyngier 8266891e25 ARM: arch_timers: switch to physical timers if HYP mode is available
If we're booted in HYP mode, it is possible that we'll run some
kind of virtualized environment. In this case, it is a better to
switch to the physical timers, and leave the virtual timers to
guests.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
2013-01-31 15:52:00 +00:00

392 lines
9.5 KiB
C

/*
* linux/drivers/clocksource/arm_arch_timer.c
*
* Copyright (C) 2011 ARM Ltd.
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/io.h>
#include <asm/arch_timer.h>
#include <asm/virt.h>
#include <clocksource/arm_arch_timer.h>
static u32 arch_timer_rate;
enum ppi_nr {
PHYS_SECURE_PPI,
PHYS_NONSECURE_PPI,
VIRT_PPI,
HYP_PPI,
MAX_TIMER_PPI
};
static int arch_timer_ppi[MAX_TIMER_PPI];
static struct clock_event_device __percpu *arch_timer_evt;
static bool arch_timer_use_virtual = true;
/*
* Architected system timer support.
*/
static inline irqreturn_t timer_handler(const int access,
struct clock_event_device *evt)
{
unsigned long ctrl;
ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
ctrl |= ARCH_TIMER_CTRL_IT_MASK;
arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
evt->event_handler(evt);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
}
static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
}
static inline void timer_set_mode(const int access, int mode)
{
unsigned long ctrl;
switch (mode) {
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
break;
default:
break;
}
}
static void arch_timer_set_mode_virt(enum clock_event_mode mode,
struct clock_event_device *clk)
{
timer_set_mode(ARCH_TIMER_VIRT_ACCESS, mode);
}
static void arch_timer_set_mode_phys(enum clock_event_mode mode,
struct clock_event_device *clk)
{
timer_set_mode(ARCH_TIMER_PHYS_ACCESS, mode);
}
static inline void set_next_event(const int access, unsigned long evt)
{
unsigned long ctrl;
ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
ctrl |= ARCH_TIMER_CTRL_ENABLE;
ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
arch_timer_reg_write(access, ARCH_TIMER_REG_TVAL, evt);
arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
}
static int arch_timer_set_next_event_virt(unsigned long evt,
struct clock_event_device *unused)
{
set_next_event(ARCH_TIMER_VIRT_ACCESS, evt);
return 0;
}
static int arch_timer_set_next_event_phys(unsigned long evt,
struct clock_event_device *unused)
{
set_next_event(ARCH_TIMER_PHYS_ACCESS, evt);
return 0;
}
static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
{
clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
clk->name = "arch_sys_timer";
clk->rating = 450;
if (arch_timer_use_virtual) {
clk->irq = arch_timer_ppi[VIRT_PPI];
clk->set_mode = arch_timer_set_mode_virt;
clk->set_next_event = arch_timer_set_next_event_virt;
} else {
clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
clk->set_mode = arch_timer_set_mode_phys;
clk->set_next_event = arch_timer_set_next_event_phys;
}
clk->cpumask = cpumask_of(smp_processor_id());
clk->set_mode(CLOCK_EVT_MODE_SHUTDOWN, NULL);
clockevents_config_and_register(clk, arch_timer_rate,
0xf, 0x7fffffff);
if (arch_timer_use_virtual)
enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
else {
enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
if (arch_timer_ppi[PHYS_NONSECURE_PPI])
enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
}
arch_counter_set_user_access();
return 0;
}
static int arch_timer_available(void)
{
u32 freq;
if (arch_timer_rate == 0) {
freq = arch_timer_get_cntfrq();
/* Check the timer frequency. */
if (freq == 0) {
pr_warn("Architected timer frequency not available\n");
return -EINVAL;
}
arch_timer_rate = freq;
}
pr_info_once("Architected local timer running at %lu.%02luMHz (%s).\n",
(unsigned long)arch_timer_rate / 1000000,
(unsigned long)(arch_timer_rate / 10000) % 100,
arch_timer_use_virtual ? "virt" : "phys");
return 0;
}
u32 arch_timer_get_rate(void)
{
return arch_timer_rate;
}
/*
* Some external users of arch_timer_read_counter (e.g. sched_clock) may try to
* call it before it has been initialised. Rather than incur a performance
* penalty checking for initialisation, provide a default implementation that
* won't lead to time appearing to jump backwards.
*/
static u64 arch_timer_read_zero(void)
{
return 0;
}
u64 (*arch_timer_read_counter)(void) = arch_timer_read_zero;
static cycle_t arch_counter_read(struct clocksource *cs)
{
return arch_timer_read_counter();
}
static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
{
return arch_timer_read_counter();
}
static struct clocksource clocksource_counter = {
.name = "arch_sys_counter",
.rating = 400,
.read = arch_counter_read,
.mask = CLOCKSOURCE_MASK(56),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static struct cyclecounter cyclecounter = {
.read = arch_counter_read_cc,
.mask = CLOCKSOURCE_MASK(56),
};
static struct timecounter timecounter;
struct timecounter *arch_timer_get_timecounter(void)
{
return &timecounter;
}
static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
{
pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
clk->irq, smp_processor_id());
if (arch_timer_use_virtual)
disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
else {
disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
if (arch_timer_ppi[PHYS_NONSECURE_PPI])
disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
}
clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
}
static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
struct clock_event_device *evt = this_cpu_ptr(arch_timer_evt);
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_STARTING:
arch_timer_setup(evt);
break;
case CPU_DYING:
arch_timer_stop(evt);
break;
}
return NOTIFY_OK;
}
static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
.notifier_call = arch_timer_cpu_notify,
};
static int __init arch_timer_register(void)
{
int err;
int ppi;
err = arch_timer_available();
if (err)
goto out;
arch_timer_evt = alloc_percpu(struct clock_event_device);
if (!arch_timer_evt) {
err = -ENOMEM;
goto out;
}
clocksource_register_hz(&clocksource_counter, arch_timer_rate);
cyclecounter.mult = clocksource_counter.mult;
cyclecounter.shift = clocksource_counter.shift;
timecounter_init(&timecounter, &cyclecounter,
arch_counter_get_cntpct());
if (arch_timer_use_virtual) {
ppi = arch_timer_ppi[VIRT_PPI];
err = request_percpu_irq(ppi, arch_timer_handler_virt,
"arch_timer", arch_timer_evt);
} else {
ppi = arch_timer_ppi[PHYS_SECURE_PPI];
err = request_percpu_irq(ppi, arch_timer_handler_phys,
"arch_timer", arch_timer_evt);
if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
ppi = arch_timer_ppi[PHYS_NONSECURE_PPI];
err = request_percpu_irq(ppi, arch_timer_handler_phys,
"arch_timer", arch_timer_evt);
if (err)
free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
arch_timer_evt);
}
}
if (err) {
pr_err("arch_timer: can't register interrupt %d (%d)\n",
ppi, err);
goto out_free;
}
err = register_cpu_notifier(&arch_timer_cpu_nb);
if (err)
goto out_free_irq;
/* Immediately configure the timer on the boot CPU */
arch_timer_setup(this_cpu_ptr(arch_timer_evt));
return 0;
out_free_irq:
if (arch_timer_use_virtual)
free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
else {
free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
arch_timer_evt);
if (arch_timer_ppi[PHYS_NONSECURE_PPI])
free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
arch_timer_evt);
}
out_free:
free_percpu(arch_timer_evt);
out:
return err;
}
static const struct of_device_id arch_timer_of_match[] __initconst = {
{ .compatible = "arm,armv7-timer", },
{ .compatible = "arm,armv8-timer", },
{},
};
int __init arch_timer_init(void)
{
struct device_node *np;
u32 freq;
int i;
np = of_find_matching_node(NULL, arch_timer_of_match);
if (!np) {
pr_err("arch_timer: can't find DT node\n");
return -ENODEV;
}
/* Try to determine the frequency from the device tree or CNTFRQ */
if (!of_property_read_u32(np, "clock-frequency", &freq))
arch_timer_rate = freq;
for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
of_node_put(np);
/*
* If HYP mode is available, we know that the physical timer
* has been configured to be accessible from PL1. Use it, so
* that a guest can use the virtual timer instead.
*
* If no interrupt provided for virtual timer, we'll have to
* stick to the physical timer. It'd better be accessible...
*/
if (is_hyp_mode_available() || !arch_timer_ppi[VIRT_PPI]) {
arch_timer_use_virtual = false;
if (!arch_timer_ppi[PHYS_SECURE_PPI] ||
!arch_timer_ppi[PHYS_NONSECURE_PPI]) {
pr_warn("arch_timer: No interrupt available, giving up\n");
return -EINVAL;
}
}
if (arch_timer_use_virtual)
arch_timer_read_counter = arch_counter_get_cntvct;
else
arch_timer_read_counter = arch_counter_get_cntpct;
return arch_timer_register();
}